We are living in disposable society, where it is easier to replace whole assemble, than find qualified technician to do actual repair.
We don't replace $5 alternator brushes, but do $500 alternator replacement.
The poppet valve in the main valve is not a rocked science and I found a site where you can buy the parts, but good luck finding service station who would stock them and have qualification to replace them.
When I had the issue, I simply found old hose fitting in my garage - the one with male thread and put it on. Problem never come back.